Dough: Combine tapioca and sweet potato flour in a mixing bowl. Add the boiling water, mix well with chopsticks. Then gather the dough together with your hand. Place the dough on a flour surface, knead the dough until smooth for about 4 to 5 minutes. Add extra tapioca flour if the dough is too soft and sticky. Roll out the dough with a rolling pin, about 0.2cm thickness. Slice the dough into strips, about 2 1/2 cm wide, then cut the strips into segments, about 2 1/2 to 3 cm.

Bring a pot of water to a rolling boil, and add the tapioca slices. When all the tapioca slices have risen, remove with a slotted spoon or wire strainer and drop it into a bowl of cold water. Drain the tapioca noodles before using.